A test evaluation method and system for a direct current commutation failure suppression strategy

Abstract

The application discloses a kind of direct current commutation failure inhibition strategy test evaluation method and system.Therein, the method includes: the model of direct current control protection system simulation model and the model of settable fault AC system;In the operating environment of direct current control protection system, the characteristic parameters of AC system are changed, the fault characteristics are changed, to realize the boundary of various direct current commutation failure inhibition strategies is tested, and the characteristic parameters of AC system are saved, including but not limited to system impedance, fault type, fault duration, fault occurrence time;Based on the characteristic parameters of AC system, the probability of various faults of AC system is normalized, the performance of inhibition strategy is evaluated, and different inhibition strategies are obtained;Considering the load loss and time length caused by commutation failure, standard electricity price calculation, the economy of different inhibition strategies is normalized, the economic benefits of different inhibition strategies are obtained, and the effect evaluation is completed.

Description

Technical Field

[0001] This invention relates to the field of power control and protection testing technology, and more specifically, to a testing method and system for a DC commutation failure suppression strategy. Background Technology

[0002] Commutation failure is one of the more common faults in DC transmission systems. It can cause an interruption in the instantaneous transmission power of the system and a rapid increase in DC current. This not only has an adverse effect on the safe and stable operation of the DC system, but also greatly shortens the life of the converter valve.

[0003] Based on the actual operation of AC / DC hybrid systems, the factors causing DC system commutation failure can be broadly categorized into two types: internal factors and external factors. Internal factors mainly involve faults related to the thyristor trigger pulse control within the converter station, such as trigger pulse loss or abnormal triggering. External factors mainly include commutation voltage, converter transformer turns ratio, DC current, and commutation reactance.

[0004] AC system faults affect both commutation voltage and DC current, and are a major cause of DC system commutation failure. When an AC system fault occurs, the amplitude of the commutation bus voltage decreases and the phase may shift. If the thyristors cannot restore their forward blocking capability before the commutation voltage reverses, the turn-off angle will be too small, causing the thyristors that were supposed to be turned off to turn back on, resulting in commutation failure in the DC system.

[0005] The commutation failure prediction module operates on a high-speed execution cycle, from AC synchronization voltage input and logic processing to subsequent execution and output. When the AC voltage changes, a single 20μs execution cycle can complete AC voltage sampling, signal processing, logic judgment, and execution output. The sensitivity of the action rate, converted to electrical angles, is 0.36°.

[0006] During commutation failure, the various control methods and strategies employed by DC control and protection may lead to mutual influence among these control strategies. Furthermore, the time delays in these control strategies result in discrepancies between the actual control effect and the predicted characteristics.

[0007] However, current testing methods for commutation only consider the response of DC control protection under common faults and normal operating conditions. They do not set up comprehensive and accurate testing methods for typical scenarios such as commutation failure. This makes it difficult to quantify and evaluate the application effect of existing DC control protection commutation failure suppression strategies, and also fails to reflect the optimization effect of domestic chip DC control protection commutation failure optimization strategies, making it difficult to meet the actual field application needs. Summary of the Invention

[0008] According to the present invention, a test and evaluation method and system for DC commutation failure suppression strategy is provided to solve the technical problem that the current related commutation test methods only consider the DC control protection response under common faults and normal operation modes, and do not set up comprehensive and accurate test methods for typical scenarios such as commutation failure. As a result, the application effect of existing DC control protection commutation failure suppression strategies is difficult to quantify and evaluate, and the optimization effect of domestic chip DC control protection commutation failure optimization strategies is not reflected, making it difficult to meet the technical needs of actual field applications.

[0009] According to a first aspect of the present invention, a test and evaluation method for a DC commutation failure suppression strategy is provided, comprising:

[0010] Build a simulation model of a DC control and protection system and a model of an AC system with configurable faults;

[0011] Under the operating environment of the DC control and protection system, the characteristic parameters of the AC system are changed to change the fault characteristics, so as to test the boundary of various DC commutation failure suppression strategies and save the characteristic parameters of the AC system, including but not limited to system impedance, fault type, fault duration, and fault occurrence time.

[0012] Based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, the performance of the suppression strategy is evaluated, and different suppression strategies are obtained.

[0013] Considering the load loss and duration caused by commutation failure, and the standard electricity price calculation, the economics of different suppression strategies are normalized and evaluated to obtain the economic benefits of different suppression strategies, and the effect evaluation is completed.

[0014] Optionally, a simulation model of a DC control and protection system is built, including:

[0015] Based on the CIGRE DC transmission standard test system, the parameters of the simulation model of the DC control and protection system were determined;

[0016] Determine the logic structure of the DC control and protection system;

[0017] Based on the parameters of the DC control and protection system simulation model and the logical structure of the DC control and protection system, a DC control and protection system simulation model is built.

[0018] Optionally, based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the suppression strategy is performance-evaluated to derive different suppression strategies, including:

[0019] When critical commutation fails, it is considered that the larger the equivalent fault impedance, i.e. the larger the transition resistance and the farther the fault location, the less likely commutation failure is to occur. The fault location is set to vary between predetermined distances. The line length parameter is determined according to the length of the AC system level. The line parameter values ​​are taken as references to the line parameter values ​​of typical voltage levels. The grounding resistance is determined according to the voltage level.

[0020] Optionally, based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the performance of the suppression strategy is evaluated, including:

[0021] When critical commutation fails, the effectiveness of various faults can be normalized based on the phase angle, fault location, volume enclosed by the transition resistance, and probability to obtain the effectiveness of different suppression strategies.

[0022] Optionally, based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the performance of the suppression strategy is evaluated, further including:

[0023] If suppression strategy 1 is applied to a 12-pulse converter, the failure volume caused by the fault location and grounding resistance at 0-30° during a single-phase ground fault is 10, and the normalized failure volume is 60. The failure volumes caused by other types of faults are 70:90:140:95:65, resulting in the phasor A1 = [180 40 20 10 5 1]. Considering the probability of occurrence, P1 = [89.16% 5.94% 1.40% 1.92% 0.70% 0.87%]. The failure effect T1 = A1.*P1.

[0024] Suppression strategy 2, the failure effect T2 = A2.*P2 is calculated;

[0025] If T1 > T2, then suppression strategy 2 is superior to strategy 1 in terms of performance;

[0026] If economic efficiency is taken into consideration, the economic loss M of commutation failure under the suppression strategy is obtained by multiplying the failure volume by the load loss PL and duration H, and then by the standard electricity price P.

[0027] In the calculation, if M1 = A1 * PL1 * H1 * P * P1; M2 = A2 * PL2 * H2 * P * P2

[0028] If the economic loss M1 of suppression strategy 1 is greater than the economic loss M2 of suppression strategy 2, then suppression strategy 2 is better than strategy 2 in terms of economics.

[0029] According to another aspect of the invention, a test and evaluation system for a DC commutation failure suppression strategy is also included, comprising:

[0030] The model building module is used to build simulation models of DC control and protection systems and models of AC systems with configurable faults;

[0031] The characteristic parameter saving module is used to change the characteristic parameters of the AC system under the operating environment of the DC control and protection system, so as to change the fault characteristics, so as to test the boundary of various DC commutation failure suppression strategies, and save the characteristic parameters of the AC system, including but not limited to system impedance, fault type, fault duration, and fault occurrence time.

[0032] A suppression strategy module is derived, which is used to normalize and evaluate the probability of various faults occurring in the AC system based on the characteristic parameters of the AC system, evaluate the performance of the suppression strategy, and derive different suppression strategies.

[0033] The evaluation and suppression strategy module is used to consider the load loss and duration caused by commutation failure, calculate the standard electricity price, normalize the economics of different suppression strategies, obtain the economic benefits of different suppression strategies, and complete the effect evaluation.

[0034] Optionally, a model module can be built, including:

[0035] The model parameter determination submodule is used to determine the parameters of the simulation model of the DC control and protection system based on the CIGRE DC transmission standard test system.

[0036] The logic structure submodule is used to determine the logic structure of the DC control and protection system.

[0037] A simulation model submodule is built to construct a simulation model of the DC control and protection system based on the parameters of the DC control and protection system simulation model and the logical structure of the DC control and protection system.

[0038] Optionally, the suppression strategy module is derived, including:

[0039] The fault location setting submodule is used to address critical commutation failures. It considers that the larger the equivalent fault impedance (i.e., the larger the transition resistance) and the farther the fault location, the less likely commutation failure is to occur. The fault location is set to vary between predetermined distances. The line length parameter is determined based on the length of the AC system level, and the line parameter values ​​are taken as references to the line parameter values ​​of typical voltage levels. The grounding resistance is determined based on the voltage level.

[0040] Optionally, the module for deriving the suppression strategy also includes:

[0041] A suppression strategy submodule is derived. When critical commutation fails, the effectiveness of various faults can be normalized according to the phase angle, fault location, volume enclosed by the transition resistance and probability, and the effectiveness of different suppression strategies can be obtained.

[0042] Optionally, the evaluation inhibition strategy module includes:

[0043] The evaluation suppression strategy submodule is used to determine the failure volume of commutation failure caused by a single-phase ground fault in a 12-pulse converter. The volume is 10, and the normalized failure volume is 60. For other types of faults, the failure volumes are 70:90:140:95:65. The resulting phasor is A1 = [180 40 20 10 5 1]. Taking into account the probability of occurrence, P1 = [89.16% 5.94% 1.40% 1.92% 0.70% 0.87%]. The failure effect is T1 = A1.*P1.

[0044] Suppression strategy 2, the failure effect T2 = A2.*P2 is calculated;

[0045] If T1 > T2, then suppression strategy 2 is superior to strategy 1 in terms of performance;

[0046] If economic efficiency is taken into consideration, the economic loss M of commutation failure under the suppression strategy is obtained by multiplying the failure volume by the load loss PL and duration H, and then by the standard electricity price P.

[0047] In the calculation, if M1 = A1 * PL1 * H1 * P * P1; M2 = A2 * PL2 * H2 * P * P2

[0048] If the economic loss M1 of suppression strategy 1 is greater than the economic loss M2 of suppression strategy 2, then suppression strategy 2 is better than strategy 2 in terms of economics.

[0049] Therefore, a test and evaluation method for DC commutation failure suppression strategies is proposed. Based on a standardized DC control and protection simulation model, and combined with the AC fault type, fault probability, fault location, transition resistance, fault duration, etc. that lead to commutation failure, a targeted test scheme is designed. The effects of various commutation failure suppression strategies are compared and analyzed, and the advantages and disadvantages of the suppression strategies are evaluated. This achieves the observability and measurability of the effect of DC control and protection commutation failure suppression strategies.

[0050] The design considers targeted testing methods under scenarios such as AC faults or disturbances, sets appropriate sampling frequencies, and evaluates existing commutation failure suppression strategies in DC engineering by changing fault types, fault locations, grounding resistance, and fault times. This aims to identify weak links in the application of different suppression strategies, achieve observable and measurable effectiveness of DC control and protection commutation failure suppression strategies, promote the optimization and upgrading of commutation failure suppression strategies, and promote the safe and stable operation of DC control and protection. Attached Figure Description

[0051] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0052] Figure 1 This is a flowchart illustrating the test and evaluation method for the DC commutation failure suppression strategy described in this embodiment.

[0053] Figure 2 This is a schematic diagram of the CIGRE DC transmission standard test system described in this embodiment;

[0054] Figure 3 This is a schematic diagram of the logic structure of the DC control and protection system described in this embodiment;

[0055] Figure 4 This is a schematic diagram of a simulation model of the control and protection device described in this embodiment;

[0056] Figure 5 This is a schematic diagram of the CFPREV control principle described in this embodiment;

[0057] Figure 6 This is a schematic diagram of the commutation failure prediction logic functional module described in this embodiment;

[0058] Figure 7 This is a block diagram of the control loop structure of the CIGRE HVDC standard test model after considering the time constant of the VDCOL loop as described in this embodiment.

[0059] Figure 8 This is a simulation comparison chart of the test results before and after optimization as described in this embodiment;

[0060] Figure 9 This is a flowchart illustrating the test and evaluation system for the DC commutation failure suppression strategy described in this embodiment. Detailed Implementation

[0061] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0062] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0063] According to a first aspect of the present invention, a test and evaluation method 100 for DC commutation failure suppression strategies is provided, with reference to... Figure 1 As shown, the method 100 includes:

[0064] S101: Build a simulation model of a DC control and protection system and a model of an AC system with configurable faults;

[0065] S102: Under the operating environment of the DC control and protection system, the characteristic parameters of the AC system are changed to change the fault characteristics, so as to test the boundary of various DC commutation failure suppression strategies and save the characteristic parameters of the AC system. The characteristic parameters of the AC system include, but are not limited to, system impedance, fault type, fault duration, and fault occurrence time.

[0066] S103: Based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, the performance of the suppression strategy is evaluated, and different suppression strategies are obtained.

[0067] S104: Considering the load loss and duration caused by commutation failure, and the standard electricity price calculation, normalize the economics of different suppression strategies, derive the economic benefits of different suppression strategies, and complete the effect evaluation.

[0068] Specifically, models of a DC system with DC control and protection system and an AC system with flexible fault settings are constructed.

[0069] Under the same DC system operating environment, the system impedance, fault type, fault duration, and fault occurrence time of the AC system are changed to change the fault characteristics, so as to test the boundaries of various DC commutation failure suppression strategies and save the above characteristic parameters of the AC system.

[0070] The probability of various failures in the aforementioned AC system is normalized and evaluated, and the performance of the suppression strategy is systematically evaluated in combination with the aforementioned AC system characteristic parameters.

[0071] Considering the load loss and duration caused by commutation failure, as well as the calculation of standard electricity prices, the economics of different consistency strategies are normalized and evaluated to obtain the economic benefits of different suppression strategies and complete the effect evaluation.

[0072] During testing, to accurately evaluate the effectiveness of different control strategies, it is recommended that the sampling frequency be 100kHz or higher, and should not be lower than 50kHz.

[0073] During testing, the larger the capacity of the AC system, the less likely commutation failure will occur. The equivalent impedance of the AC system is generally between 1 and 10 times that of the equivalent impedance of the DC system.

[0074] During testing, the total fault duration of the AC system was set to 100ms, and the fault duration of the transition fault was 3-200ms followed by 100ms.

[0075] During testing, the control characteristics of different pulsating converters are taken into account. For single-phase ground faults, only the phase angle variation range of 0-360° / commutation pulsation number needs to be considered, and it needs to be multiplied by half of the pulsation number when normalizing. For other types of faults, the phase angle variation range of 0-180° needs to be considered.

[0076] During testing, if the AC system is 220kV-500kV, the probability of occurrence of various fault types, such as single-phase grounding fault, two-phase grounding fault, two-phase fault, three-phase fault, transition fault, and non-full-phase to single-phase fault, can be set to 89.16%, 5.94%, 1.40%, 1.92%, 0.70%, and 0.87%. For other voltage levels, the probability of occurrence can be adjusted according to the local fault probability.

[0077] When critical commutation fails, it is considered that the larger the equivalent fault impedance (i.e., the larger the transition resistance) and the farther the fault location, the less likely commutation failure is to occur. The fault location is set to vary between 0 and L km. The line length L can be 300 km for a 500kV rating. The line parameter values ​​are taken as typical voltage level line parameters. The grounding resistance is considered to be 300Ω for 500kV.

[0078] When critical commutation fails, the effectiveness of various faults can be normalized based on the phase angle, fault location, volume enclosed by the transition resistance, and probability to obtain the effectiveness of different suppression strategies. The smaller the volume, the better the suppression strategy.

[0079] The effectiveness of the evaluated suppression strategies is normalized by combining economic factors. The economic factors can be calculated by multiplying the load loss and duration caused by commutation failure by the standard electricity price to obtain the cost. Thus, the economic benefits of different suppression strategies are obtained. The higher the cost, the worse the economic benefits and the less effective the suppression strategy.

[0080] A simulation model of the DC control and protection system was built using PSCAD / EMTDC simulation software. Its parameters can be referenced from the CIGRE DC transmission standard test system, as shown in the attached figure. Figure 2 As shown in the attached figure, the logic structure of the DC control and protection system is as follows. Figure 3 As shown, the simulation model diagram of the control and protection device is as follows: Figure 4 As shown.

[0081] The existing DC control and protection platform converter control device has an AC synchronization voltage acquisition period of 24μs, corresponding to a sampling frequency of 41.67kHz. Based on the performance of the independently controllable high-speed communication bus and processor, the following optimizations were made: the AC synchronization voltage is acquired and processed by a separate acquisition board with a sampling period of 10μs, corresponding to a sampling frequency of 100kHz, and the sensitivity of the action rate converted to an electrical angle of 0.36°.

[0082] To accurately compare and test the results, the sampling frequency can be set to 100kHz or higher. Figure 5 As shown, it has simulation capabilities to define logic for different execution cycles and testing capabilities to compare action sensitivity. It enables faster and more precise control testing and verification by implementing a method for calculating the commutation arc overlap area considering DC variations and predictive control of the commutation margin area difference. Figure 6 As shown.

[0083] To test and evaluate the effectiveness of the commutation failure suppression strategy, fault conditions and operating modes were set based on the aforementioned CIGRE standard test model, combined with grid fault conditions and typical interference conditions. Specifically, the maximum allowable increase in DC current was set to 1.8 times the rated value, and the minimum allowable decrease in DC voltage was set to the lowest DC voltage value in VDCOL, 0.4UdN.

[0084] A ground fault is set on the outgoing line on the inverter side, and the AC system fault is simulated at different distances from the converter bus using adjustable fault type, fault phase angle, fault location, and grounding resistance.

[0085] The focus is on examining the responses of physical quantities such as the turn-off angle (arc extinction angle), DC current, DC voltage, converter bus voltage, and low-voltage current limiter start-up voltage after a fault. Specifically, the turn-off angle response curve is used to determine whether DC transmission commutation has failed. Generally, the turn-off angle γ must be greater than the inherent limit turn-off angle γmin, taken as 7.2°; otherwise, DC transmission commutation is considered failed. The DC current and DC voltage response curves are used to observe the fault recovery process duration and the stable operating point of the DC system after the fault. The converter bus voltage response curve is compared with the DC voltage response curve to verify that the converter bus voltage fluctuates less than the DC voltage. The low-voltage current limiter start-up voltage response curve is used to observe the changes in the low-voltage current limiter start-up voltage after the fault and its steady-state value after the fault. For ease of comparison, the response curves of these five physical quantities under different control methods are usually placed in the same coordinate system for testing and evaluation.

[0086] refer to Figure 7As shown, the simulation model considers the influence of the time constant of the VDCOL (Voltage Dependent Current Order Limiters) stage, characterizing the first-order inertial stage of the VDCOL stage. Here, T represents the time constant of the VDCOL stage, where the starting voltage of the low-voltage current limiter changes from U to U′. The typical time constant for VDCOL stage activation is T = 10ms. Since DC lines are generally long, there is a certain delay in signal transmission. For example, from detecting a change in the AC converter bus voltage at the inverter station to transmitting this signal through the remote control channel to the rectifier station and entering the VDCOL stage entrance on the rectifier side, it typically takes 20–30ms (when the DC line is 1000km). The signal transmission delay is taken as the midpoint of 20–30ms, 25ms.

[0087] During testing, the system impedance of the AC system is typically taken to be between 1 and 10 times that of the equivalent impedance of the DC system. The total fault duration of the AC system is taken as 100ms, and the fault duration of the transition fault is 3-200ms followed by a 100ms delay.

[0088] Taking into account the control characteristics of different pulsating converters, in the case of a single-phase ground fault, only the phase angle variation range of 0-360° / commutation pulsation number needs to be considered, and it needs to be multiplied by half of the pulsation number when normalizing; in other types of faults, the phase angle variation range of 0-180° needs to be considered.

[0089] During testing, if the AC system is 220kV-500kV, the probability of occurrence of various fault types, such as single-phase grounding fault, two-phase grounding fault, two-phase fault, three-phase fault, and transitional fault, can be set to 89.16%, 5.94%, 1.40%, 1.92%, 0.70%, and 0.87%, respectively. For other voltage levels, the probability of occurrence can be adjusted according to the local fault probability.

[0090] When critical commutation failure occurs, it is considered that the larger the equivalent fault impedance (i.e., the larger the transition resistance) and the farther the fault location, the less likely commutation failure is to occur. The fault location is set to vary between 0 and L km, and the line length L can be taken as a typical line parameter based on a 500kV rating of 300km. The grounding resistance is considered based on the voltage level: 300Ω for 500kV and 600Ω for 1000kV.

[0091] Using the continuous simulation capabilities of EMTDC, the spatiotemporal distribution patterns of commutation failure faults were described, and the basic characteristics of commutation failure under six representative ground short-circuit faults were analyzed in detail. The solution of the critical impedance for commutation failure was reduced to an optimization problem, and an objective function considering the critical commutation failure condition was proposed. Furthermore, the fault location and grounding resistance at a specific fault type were quickly determined using the EMTDC optimization simulation program.

[0092] When critical commutation fails, the effectiveness of various faults can be normalized based on the phase angle, fault location, volume enclosed by the transition resistance, and probability to obtain the effectiveness of different suppression strategies. The smaller the volume, the better the suppression strategy.

[0093] If suppression strategy 1 is applied to a 12-pulse converter, the failure volume caused by the fault location and grounding resistance during a single-phase ground fault (0-30°) resulting in commutation failure is 10, and the normalized failure volume is 60; while the failure volumes caused by other types of faults are 70:90:140:95:65, the phasor quantity A1 = [180 40 20 10 5 1] is obtained; and considering the probability of occurrence, P1 = [89.16% 5.94% 1.40% 1.92% 0.70% 0.87%]. The failure effect T1 = A1 * P1.

[0094] Suppression strategy 2, the failure effect T2 = A2.*P2 is calculated.

[0095] If T1 > T2, then suppression strategy 2 outperforms strategy 1 in terms of performance.

[0096] If economic efficiency is considered, the economic loss M of commutation failure under the suppression strategy is obtained by multiplying the failure volume by the load loss PL and duration H, and then by the standard electricity price P.

[0097] In the calculation, if M1 = A1 * PL1 * H1 * P * P1; M2 = A2 * PL2 * H2 * P * P2

[0098] If the economic loss M1 of suppression strategy 1 is greater than the economic loss M2 of suppression strategy 2, then suppression strategy 2 is superior to strategy 3 in terms of economic efficiency. The simulation comparison of the test results before and after optimization is shown in the figure below. Figure 8 As shown.

[0099] Therefore, a test and evaluation method for DC commutation failure suppression strategies is proposed. Based on a standardized DC control and protection simulation model, and combined with the AC fault type, fault probability, fault location, transition resistance, fault duration, etc. that lead to commutation failure, a targeted test scheme is designed. The effects of various commutation failure suppression strategies are compared and analyzed, and the advantages and disadvantages of the suppression strategies are evaluated. This achieves the observability and measurability of the effect of DC control and protection commutation failure suppression strategies.

[0100] The design considers targeted testing methods under scenarios such as AC faults or disturbances, sets appropriate sampling frequencies, and evaluates existing commutation failure suppression strategies in DC engineering by changing fault types, fault locations, grounding resistance, and fault times. This aims to identify weak links in the application of different suppression strategies, achieve observable and measurable effectiveness of DC control and protection commutation failure suppression strategies, promote the optimization and upgrading of commutation failure suppression strategies, and promote the safe and stable operation of DC control and protection.

[0101] Optionally, a simulation model of a DC control and protection system is built, including:

[0102] Based on the CIGRE DC transmission standard test system, the parameters of the simulation model of the DC control and protection system were determined;

[0103] Determine the logic structure of the DC control and protection system;

[0104] Based on the parameters of the DC control and protection system simulation model and the logical structure of the DC control and protection system, a DC control and protection system simulation model is built.

[0105] Optionally, based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the suppression strategy is performance-evaluated to derive different suppression strategies, including:

[0106] When critical commutation fails, it is considered that the larger the equivalent fault impedance, i.e. the larger the transition resistance and the farther the fault location, the less likely commutation failure is to occur. The fault location is set to vary between predetermined distances. The line length parameter is determined according to the length of the AC system level. The line parameter values ​​are taken as references to the line parameter values ​​of typical voltage levels. The grounding resistance is determined according to the voltage level.

[0107] Optionally, based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the performance of the suppression strategy is evaluated, including:

[0108] When critical commutation fails, the effectiveness of various faults can be normalized based on the phase angle, fault location, volume enclosed by the transition resistance, and probability to obtain the effectiveness of different suppression strategies.

[0109] Optionally, based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the performance of the suppression strategy is evaluated, further including:

[0110] If suppression strategy 1 is applied to a 12-pulse converter, the failure volume caused by the fault location and grounding resistance at 0-30° during a single-phase ground fault is 10, and the normalized failure volume is 60. The failure volumes caused by other types of faults are 70:90:140:95:65, resulting in the phasor A1 = [180 40 20 10 5 1]. Considering the probability of occurrence, P1 = [89.16% 5.94% 1.40% 1.92% 0.70% 0.87%]. The failure effect T1 = A1.*P1.

[0111] Suppression strategy 2, the failure effect T2 = A2.*P2 is calculated;

[0112] If T1 > T2, then suppression strategy 2 is superior to strategy 1 in terms of performance;

[0113] If economic efficiency is taken into consideration, the economic loss M of commutation failure under the suppression strategy is obtained by multiplying the failure volume by the load loss PL and duration H, and then by the standard electricity price P.

[0114] In the calculation, if M1 = A1 * PL1 * H1 * P * P1; M2 = A2 * PL2 * H2 * P * P2

[0115] If the economic loss M1 of suppression strategy 1 is greater than the economic loss M2 of suppression strategy 2, then suppression strategy 2 is better than strategy 2 in terms of economics.

[0116] According to another aspect of the present invention, a test and evaluation system 900 for DC commutation failure suppression strategies is also provided, with reference to Figure 9 As shown, the system 900 includes:

[0117] Model building module 910 is used to build simulation models of DC control and protection systems and models of AC systems with configurable faults;

[0118] The characteristic parameter saving module 920 is used to change the characteristic parameters of the AC system under the operating environment of the DC control and protection system, so as to change the fault characteristics, so as to test the boundary of various DC commutation failure suppression strategies, and save the characteristic parameters of the AC system, including but not limited to system impedance, fault type, fault duration, and fault occurrence time.

[0119] The suppression strategy module 930 is used to normalize and evaluate the probability of various faults occurring in the AC system based on the characteristic parameters of the AC system, evaluate the performance of the suppression strategy, and obtain different suppression strategies.

[0120] The evaluation suppression strategy module 940 is used to consider the load loss and duration caused by commutation failure, calculate the standard electricity price, normalize the economics of different suppression strategies, obtain the economic benefits of different suppression strategies, and complete the effect evaluation.

[0121] Optionally, a model module can be built, including:

[0122] The model parameter determination submodule is used to determine the parameters of the simulation model of the DC control and protection system based on the CIGRE DC transmission standard test system.

[0123] The logic structure submodule is used to determine the logic structure of the DC control and protection system.

[0124] A simulation model submodule is built to construct a simulation model of the DC control and protection system based on the parameters of the DC control and protection system simulation model and the logical structure of the DC control and protection system.

[0125] Optionally, the suppression strategy module is derived, including:

[0126] The fault location setting submodule is used to address critical commutation failures. It considers that the larger the equivalent fault impedance (i.e., the larger the transition resistance) and the farther the fault location, the less likely commutation failure is to occur. The fault location is set to vary between predetermined distances. The line length parameter is determined based on the length of the AC system level, and the line parameter values ​​are taken as references to the line parameter values ​​of typical voltage levels. The grounding resistance is determined based on the voltage level.

[0127] Optionally, the module for deriving the suppression strategy also includes:

[0128] A suppression strategy submodule is derived for use in critical commutation failure. The effectiveness of various faults can be normalized based on phase angle, fault location, volume enclosed by transition resistance, and probability to obtain the effectiveness of different suppression strategies.

[0129] Optionally, the evaluation inhibition strategy module includes:

[0130] The evaluation suppression strategy submodule is used to determine the failure volume of commutation failure caused by a single-phase ground fault in a 12-pulse converter. The volume is 10, and the normalized failure volume is 60. For other types of faults, the failure volumes are 70:90:140:95:65. The resulting phasor is A1 = [180 40 20 10 5 1]. Taking into account the probability of occurrence, P1 = [89.16% 5.94% 1.40% 1.92% 0.70% 0.87%]. The failure effect is T1 = A1.*P1.

[0131] Suppression strategy 2, the failure effect T2 = A2.*P2 is calculated;

[0132] If T1 > T2, then suppression strategy 2 is superior to strategy 1 in terms of performance;

[0133] If economic efficiency is taken into consideration, the economic loss M of commutation failure under the suppression strategy is obtained by multiplying the failure volume by the load loss PL and duration H, and then by the standard electricity price P.

[0134] In the calculation, if M1 = A1 * PL1 * H1 * P * P1; M2 = A2 * PL2 * H2 * P * P2

[0135] If the economic loss M1 of suppression strategy 1 is greater than the economic loss M2 of suppression strategy 2, then suppression strategy 2 is better than strategy 2 in terms of economics.

[0136] The test and evaluation system 900 for a DC commutation failure suppression strategy according to an embodiment of the present invention corresponds to the test and evaluation method 100 for a DC commutation failure suppression strategy according to another embodiment of the present invention, and will not be described again here.

[0137] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0138] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0139] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0140] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0141] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0142] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A test and evaluation method for a DC commutation failure suppression strategy, characterized in that, include: Build a simulation model of a DC control and protection system and a model of an AC system with configurable faults; Under the operating environment of the DC control and protection system, the characteristic parameters of the AC system are changed to change the fault characteristics, so as to test the boundary of various DC commutation failure suppression strategies and save the characteristic parameters of the AC system, including system impedance, fault type, fault duration, and fault occurrence time. Based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, the performance of the suppression strategy is evaluated, and different suppression strategies are obtained. Considering the load loss and duration caused by commutation failure and the standard electricity price calculation, the economics of different suppression strategies are normalized and evaluated to obtain the economic benefits of different suppression strategies and complete the effect evaluation. Based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the performance of the suppression strategies is evaluated to obtain different suppression strategies, including: When critical commutation fails, it is considered that the larger the equivalent fault impedance, that is, the larger the transition resistance and the farther the fault location, the less likely it is to fail commutation. The fault location is set to vary between predetermined distances. The line length parameter value is determined according to the length of the AC system level. The line parameter values ​​are taken as references to the line parameter values ​​of typical voltage levels. The grounding resistance is determined according to the voltage level. Based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the performance of the suppression strategy is evaluated, including: When critical commutation fails, the effectiveness of various faults is normalized based on the phase angle, fault location, volume enclosed by the transition resistance, and probability to obtain the effectiveness of different suppression strategies. Based on the characteristic parameters of the AC system, the probability of various faults occurring in the AC system is normalized and evaluated, and the performance of the suppression strategy is evaluated. This also includes: If suppression strategy 1 is applied to a 12-pulse converter, the failure volume caused by the fault location and grounding resistance at 0-30° during a single-phase ground fault is 10, and the normalized failure volume is 60. The failure volumes caused by other types of faults are 70:90:140:95:65, resulting in the phasor quantity A1 = [180 40 20 10 5 1]. Considering the probability of occurrence, P1 = [89.16% 5.94% 1.40% 1.92% 0.70% 0.87%]. The failure effect T1 = A1 × P1. Suppression strategy 2, the failure effect is calculated to be T2 = A2 × P2; If T1 > T2, then suppression strategy 2 is superior to strategy 1 in terms of performance; If economic efficiency is taken into consideration, the economic loss M of commutation failure under the suppression strategy is obtained by multiplying the failure volume by the load loss PL and duration H, and then by the standard electricity price P. In the calculation, if M1 = A1 × PL1 × H1 × P × P1; M2 = A2 × PL2 × H2 × P × P2 If the economic loss M1 of suppression strategy 1 is greater than the economic loss M2 of suppression strategy 2, then suppression strategy 2 is better than strategy 3 in terms of economic efficiency. The failure volume is the volume enclosed by the phase angle, fault location, and transition resistance.

2. The method according to claim 1, characterized in that, Build a simulation model of the DC control and protection system, including: Based on the CIGRE DC transmission standard test system, the parameters of the simulation model of the DC control and protection system are determined; Determine the logic structure of the DC control and protection system; Based on the parameters of the DC control and protection system simulation model and the logical structure of the DC control and protection system, a DC control and protection system simulation model is built.

3. A test and evaluation system for a DC commutation failure suppression strategy, characterized in that, include: The model building module is used to build simulation models of DC control and protection systems and models of AC systems with configurable faults; The characteristic parameter saving module is used to change the characteristic parameters of the AC system under the operating environment of the DC control and protection system, so as to change the fault characteristics, so as to test the boundary of various DC commutation failure suppression strategies, and save the characteristic parameters of the AC system, including system impedance, fault type, fault duration, and fault occurrence time. A suppression strategy module is derived, which is used to normalize and evaluate the probability of various faults occurring in the AC system based on the characteristic parameters of the AC system, evaluate the performance of the suppression strategy, and derive different suppression strategies. The evaluation and suppression strategy module is used to consider the load loss and duration caused by commutation failure, calculate the standard electricity price, normalize the economics of different suppression strategies, obtain the economic benefits of different suppression strategies, and complete the effect evaluation. The suppression strategy module is derived, including: The fault location setting submodule is used to consider that when critical commutation failure occurs, the larger the equivalent fault impedance (i.e., the larger the transition resistance) and the farther the fault location is, the less likely commutation failure will occur. The fault location is set to vary between predetermined distances. The line length parameter value is determined according to the length of the AC system level. The line parameter values ​​are taken as references to the line parameter values ​​of typical voltage levels. The grounding resistance is determined according to the voltage level. The module for deriving the suppression strategy also includes: A suppression strategy submodule is derived, which is used to normalize the effectiveness of various faults under critical commutation failure based on phase angle, fault location, volume enclosed by transition resistance and probability, and to obtain the effectiveness of different suppression strategies. The evaluation and suppression strategy module includes: The evaluation suppression strategy submodule is used to determine the failure volume of commutation failure caused by a single-phase ground fault in a 12-pulse converter. The volume is 10, and the normalized failure volume is 60. The failure volumes caused by other types of faults are 70:90:140:95:

65. This yields the phasor quantity A1 = [180 40 2010 5 1]. Taking into account the probability of occurrence, P1 = [89.16% 5.94% 1.40% 1.92% 0.70% 0.87%], the failure effect T1 = A1 × P1. Suppression strategy 2, the failure effect is calculated to be T2 = A2 × P2; If T1 > T2, then suppression strategy 2 is superior to strategy 1 in terms of performance; If economic efficiency is taken into consideration, the economic loss M of commutation failure under the suppression strategy is obtained by multiplying the failure volume by the load loss PL and duration H, and then by the standard electricity price P. In the calculation, if M1 = A1 × PL1 × H1 × P × P1; M2 = A2 × PL2 × H2 × P × P2 If the economic loss M1 of suppression strategy 1 is greater than the economic loss M2 of suppression strategy 2, then suppression strategy 2 is better than strategy 3 in terms of economic efficiency. The failure volume is the volume enclosed by the phase angle, fault location, and transition resistance.

4. The system according to claim 3, characterized in that, The model building module includes: The model parameter determination submodule is used to determine the parameters of the simulation model of the DC control and protection system based on the CIGRE DC transmission standard test system. The logic structure submodule is used to determine the logic structure of the DC control and protection system. A simulation model submodule is built to construct a simulation model of the DC control and protection system based on the parameters of the DC control and protection system simulation model and the logical structure of the DC control and protection system.

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